2 Pistons who are expendable in the right deal
I know there are plenty of fans who would put Stewart on the first list. Stewart's shooting has become one of the scapegoats for the Pistons' poor start. He has had a bad stretch offensively, there is no doubt, but the team also falls apart defensively when he leaves the game, he's the only big who can switch on the perimeter and is the only one who regularly affects shots at the rim.
The answer might be to just move him to backup center, as his long-range shooting would be more of a factor. In the right deal, Stewart is a guy they could move, but he's not the reason they are bad.
I would not trade Jaden Ivey unless there was a proven player coming back who was an obvious fit. Ivey has found himself in Monty Williams' doghouse for much of the season, but he should eventually be better for it, even if I don't agree with how he has been handled.
Ivey is the Pistons' best trade asset, but they can't give him away just to make a move, especially when his value is low. Even if they moved him for a more proven player, they have to make sure he isn't just a more expensive version, as Ivey's early stats are comparable to a young Zach LaVine, so swapping the two is a move the Pistons would almost certainly regret considering Ivey is on a rookie deal.
If the right player becomes available (OG Anunoby) the Pistons will have to consider if Ivey is the long-term fit with Cade Cunningham, but they can't move him unless there is a proven impact player coming back.